From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65D8AC43331 for ; Fri, 6 Sep 2019 15:18:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 43947214DE for ; Fri, 6 Sep 2019 15:18:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391203AbfIFPSm (ORCPT ); Fri, 6 Sep 2019 11:18:42 -0400 Received: from foss.arm.com ([217.140.110.172]:58064 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390233AbfIFPSm (ORCPT ); Fri, 6 Sep 2019 11:18:42 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A95341576; Fri, 6 Sep 2019 08:18:41 -0700 (PDT) Received: from [10.1.196.105] (unknown [10.1.196.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 8B82E3F59C; Fri, 6 Sep 2019 08:18:38 -0700 (PDT) From: James Morse Subject: Re: [PATCH v3 07/17] arm64, hibernate: move page handling function to new trans_pgd.c To: Pavel Tatashin References: <20190821183204.23576-1-pasha.tatashin@soleen.com> <20190821183204.23576-8-pasha.tatashin@soleen.com> Cc: jmorris@namei.org, sashal@kernel.org, ebiederm@xmission.com, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, corbet@lwn.net, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, marc.zyngier@arm.com, vladimir.murzin@arm.com, matthias.bgg@gmail.com, bhsharma@redhat.com, linux-mm@kvack.org, mark.rutland@arm.com Message-ID: Date: Fri, 6 Sep 2019 16:18:37 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190821183204.23576-8-pasha.tatashin@soleen.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Pavel, On 21/08/2019 19:31, Pavel Tatashin wrote: > Now, that we abstracted the required functions move them to a new home. > Later, we will generalize these function in order to be useful outside > of hibernation. > diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c > new file mode 100644 > index 000000000000..00b62d8640c2 > --- /dev/null > +++ b/arch/arm64/mm/trans_pgd.c > @@ -0,0 +1,211 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +/* > + * Copyright (c) 2019, Microsoft Corporation. > + * Pavel Tatashin Hmmm, while line-count isn't a useful metric: this file contains 41% of the code that was in hibernate.c, but has stripped the substantial copyright-pedigree that the hibernate code had built up over the years. (counting lines identified by 'cloc' as code, not comments or blank) If you are copying or moving a non trivial quantity of code, you need to preserve the copyright. Something like 'Derived from the arm64 hibernate support which has:'.... > + */ > + > +/* > + * Transitional tables are used during system transferring from one world to > + * another: such as during hibernate restore, and kexec reboots. During these > + * phases one cannot rely on page table not being overwritten. I think you need to mention that hibernate and kexec are rewriting memory, and may overwrite the live page tables, therefore ... > + * > + */ > + > +#include > +#include > +#include > +#include #include #include #include > +static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr) > +{ > + pte_t pte = READ_ONCE(*src_ptep); > + > + if (pte_valid(pte)) { > + /* > + * Resume will overwrite areas that may be marked > + * read only (code, rodata). Clear the RDONLY bit from > + * the temporary mappings we use during restore. > + */ > + set_pte(dst_ptep, pte_mkwrite(pte)); > + } else if (debug_pagealloc_enabled() && !pte_none(pte)) { > + /* > + * debug_pagealloc will removed the PTE_VALID bit if > + * the page isn't in use by the resume kernel. It may have > + * been in use by the original kernel, in which case we need > + * to put it back in our copy to do the restore. > + * > + * Before marking this entry valid, check the pfn should > + * be mapped. > + */ > + BUG_ON(!pfn_valid(pte_pfn(pte))); Thanks, James